Polycrystalline diamond (PCD) materials known in the art are made by subjecting a volume of diamond grains to high pressure/high temperature (HPHT) conditions in the presence of a catalyst material, such as a solvent catalyst metal. Such PCD materials are known for having a high degree of wear resistance, making them a popular material choice for use in such industrial applications as cutting tools for machining, and wear and cutting elements that are used in subterranean mining and drilling, where such high degree of wear resistance is desired. In such applications, conventional PCD materials can be provided in the form of a surface layer or a material body of, e.g., a cutting element used with cutting and drilling tools, to impart desired levels of wear resistance thereto.
Traditionally, PCD cutting elements used in such applications comprise a PCD body that is attached to a suitable substrate. Substrates used in such cutting element applications include carbides such as cemented tungsten carbide (WC—Co) that operate to facilitate attachment of the PCD cutting element to an end use device, such as a drill bit, by welding or brazing process.
Such conventional PCD comprises about 10 percent by volume of a catalyst material to facilitate intercrystalline bonding between the diamond grains, and to bond the PCD material to the underlying substrate. Catalyst materials that are conventionally used for this purpose include solvent catalyst metals, such as those selected from Group VIII of the Periodic table including cobalt, iron, nickel, and mixtures thereof.
The amount of catalyst material used to form PCD materials represents a compromise between desired properties of thermal stability, toughness, strength, hardness, and wear resistance. A higher metal catalyst content typically produces a PCD material having increased toughness, but decreased thermal stability (due both to the catalytic and expansion properties of the metal catalyst at elevated operating temperatures), and decreased hardness and wear resistance. Thus, such resulting PCD material may not be well suited for use in applications calling for a high degree of thermal stability, hardness or wear resistance, but may be well suited for applications calling for a high degree of toughness.
Conversely, a lower metal catalyst content typically produces a PCD material having increased properties of thermal stability, hardness and wear resistance, but reduced toughness. Thus, such resulting PCD material may not be well suited for use in applications calling for a high degree of toughness, but may be well suited for applications calling for a high degree of thermal stability, hardness or wear resistance.
Accordingly, the amount of the catalyst or metal material that is used to make PCD materials represents a compromise that is dependent on the desired properties of the PCD material for a particular end-use application. In addition to the properties of the PCD material, when the PCD construction is provided in the form of a PCD cutting element or compact comprising a substrate, the amount of the metal component in the substrate may also impact both the composition of the PCD body and the performance properties of the substrate. For example, when the substrate is used as the source of the catalyst or metal material during the process of making the PCD body by HPHT process, the content of the catalyst material within the substrate can and will impact the amount of catalyst material that infiltrates into the diamond grain volume and that resides in the resulting PCD material.
Additionally, the amount of the catalyst or metal material in the substrate can impact the performance of the cutting element during operation. For example, when the cutting element is used in a subterranean drilling operation with a drill bit, substrates having a high metal content can erode during use, which can reduce the effective service life of the cutting element.
It is, therefore, desired that a PCD construction be developed in a manner that provides a desired level of thermal stability, toughness, strength, hardness, and wear resistance making the construction useful as a cutting element for applications calling for the same such as subterranean drilling to thereby provide an improved service live when compared to conventional PCD materials. It is further desired that such PCD construction be developed in a matter that reduces unwanted erosion of the substrate when placed into use applications, such as subterranean drilling, where the construction is exposed to an erosive operating environment.